Former Cardiff City chairman Sam Hammam has been accused of "total greed and self-interest" over the negotiations to sell his controlling stake in the club.

Hammam agreed to the £27m takeover deal just 15 minutes before the threat of Cardiff going into administration.

But one of the men behind Cardiff's new stadium project has revealed Hammam demanded an extra £500,000 before finally walking away from the club.

"That was money which would have been spent on players," said Mike Hall.

"But instead it's gone into Sam's pocket. It was the only way the deal was going to be done.

"I know people say he's a complex character, but at the end it was total greed and self-interest.

I know who some of the investors are and I think people will be surprised when it's released

Cardiff stadium developer Mike Hall

"Unfortunately at the death, the football club had to agree to pay another £500,000 to Rudgwick, Sam's company.

"And would you believe, another £90,000 was paid to his brother on top of the agreement to pay back the majority of the loan notes [worth £24m].

"It was amazing, but football is a murky world."

Hammam took over at Cardiff six years ago when they were languishing in the bottom division of the Football League.

The Lebanese-born businessman transformed them into a club chasing Premiership promotion, but failed to secure planning permission on plans for a new 30,000-seater stadium.

Cardiff Council had been reluctant to give the project the green light because of concerns over its financial viability.

Hammam agreed to sell his 82.5% share in October after Peter Ridsdale, brought in by Hammam to force through the new stadium project, found new investors willing to take over.

The change at the top was welcomed by the council, who then recommended for approval the club's business plan for the new stadium.

But negotiations between the club and Hammam became strained this week, putting the club's future and new stadium in doubt.

There were fears that Cardiff could have been put into administration if a deal was not done by noon on Friday, but a triumphant Ridsdale announced Hammam had agreed to sell 15 minutes before the deadline.

But Hall, a director of the stadium developers PMG Estates, said Hammam's demands and negotiation tactics left a lot to be desired.

"We were dragged right into it to settle this with Sam," former Wales rugby captain Hall told BBC Wales Sport.

"There was an awful lot at stake for us as the developers and the council who have worked very had on this [new stadium] for the past four or five years.

Hall says work on Cardiff's new stadium could start in March

"Basically it came down to money and people need to be very careful here in the way they look back at Sam.

"Some people will look back with rose tinted spectacles no doubt, but at the end it was total greed and self-interest."

Cardiff hope to start work on the new stadium at Leckwith in March next year following the end of the 90-day judicial review period for the planning application.

The club has yet to sign a building contract with construction firm Laing O'Rourke, and Hall said there were "a few other hurdles to overcome".

Ridsdale, who takes over Hammam's role as Cardiff chairman, announced in October the new investment would come from London-based financial institutions who specialise in hedge funds.

But Hall has now revealed the money is coming from sources much closer to home.

He said: "I know who some of the investors are and I think people will be surprised when it's released.

"They are local investors; people who are interested in the football club and interested in its long-term future.

"It's not the hedge funds that everybody's been talking about."

The identity of the new investors will be made public during the club's EGM on Monday, 15 January.

Hammam declined to respond to Hall's comments when he was contacted by BBC Wales Sport on Saturday.

But revealed he would be at Leicester to watch Cardiff's Championship match at the Walkers Stadium.